1. Field of the Invention
The invention relates to a stock inlet, in particular a multi-layer stock inlet, of a paper machine having at least one stock suspension supply, a diffusor block with a multitude of tubular elements, and a stock inlet aperture which has a number of suspension conduits running the width of the machine, which are formed between a top and bottom wall of the stock inlet aperture by at least two, preferably three, dividing elements which run the width of the machine and through which the stock suspension is conveyed onto a wire or between two wires, with the suspension conduits having a first region I and a second region II disposed downstream, with the first region I being constituted by flat boundary surfaces, which run the width of the machine and converge in the flow direction, and with each dividing element having a sharper convergence of its surfaces in the second region II than in the first region I.
2. Discussion of Background Information
A similar stock inlet is known, for example, from the Applicant's U.S. Pat. No. 5,599,428. Among other things, this document shows a stock inlet in FIG. 6, which has a stock inlet aperture with three internal dividing elements that separate the stock suspension of the individual layers of this stock inlet from one another. In the aperture outlet region, the dividing elements first have a widening and then a tapering (convergence) which should lead to there being only minimal mixing tendencies between the individual suspension layers that are brought together after the dividing elements.
A problem of these known stock inlets lies in the fact that the paper produced therewith has a striped structure, known as "tiger stripes," running the width of the machine, whose origin has not yet been definitively explained. These stripes, which are distinguished by alternating areas of higher and lower luster and extend in the machine direction, are particularly undesirable in high-quality papers and should be prevented to the greatest extent possible.
The Applicant's as yet unpublished DE 199 02 621.1 describes a stock inlet with lamellas to counteract tiger stripes. Lamellas of this kind also have a particularly positive effect on the jet quality.
U.S. Pat. No. 5,876,564 discloses building up angular momentum in the turbulence generator in order to increase the lateral strength and to keep the L/C ratio as low as possible, which is of particular interest for gap formers. A disadvantage of such an angular momentum generator, however, is the low jet quality and poor formation.